Taking the genus as Dockrilia, I looked through all the Dockrillia at Jay Pfahl's Internet Orchid Species Photo Encyclopedia - teretifolium and schoenina both have different colour markings there - the closest picture is for Dockrillia chordiformis, and the leaves look correct in the background too (IOSPE PHOTOS). So I think that would be my best guess for now. Thanks for all the help - no way I would have found it on my own!